The subject matter disclosed herein relates to a combustor having a premixed injector.
In turbine engines and, in particular, gas turbine engines, fuels, such as gas and compressed air, are fed to a combustor where combustion thereof occurs. High temperature fluids generated from this combustion are then directed through a transition piece and into a turbine for power and/or electricity generation. Generally, the compressed air is fed to the combustor from a compressor and travels upstream toward the head end where it is mixed with the other fuels.
When the fuel/air mixture is combusted certain pollutants, such as Nitrous Oxides (NOx), are produced. Since NOx production is generally undesirable, recent efforts have been undertaken to reduce NOx production and emission. In some cases, these efforts have centered on encouraging more complete mixing of the air and fuel. In these and/or other cases, late lean injection (LLI) has also been employed.
The purpose of LLI is to reduce NOx formation by reducing the residence time of fuel and air within the combustor. This is achieved by injecting a portion of the fuel and air into the combustor at an axial location downstream from the main combustion zone. In this way, the LLI fuel and air are combusted but do not travel as far through the combustor as they otherwise would. As such, as long as sufficient fuel and air mixing occurs, the LLI fuel and air generally do not form as much NOx as would otherwise be produced.